Radar apparatuses discharge an electromagnetic wave from an antenna toward a specific direction or all directions, and receive an echo signal to detect a target object from a level of the echo signal. The target objects are rendered on displays. The radar apparatuses are applied to a wide range of fields, such as ships and airplanes.
However, the conventional radar apparatus, if applied to a ship radar, may detect a target object which does not originally exist when seen from a ship equipped with the radar apparatus (hereinafter, referred to as a “ship concerned”), as an echo signal from the target object, for example. A radar image caused by such a target object not originally existing is referred to as a “fake image.” The fake image may be produced from side lobes of the electromagnetic wave discharged from the antenna. However, other types of fake images may be produced, which do not cause side lobes. For example, a fake image which is typically detected such that a second target object exists behind a first target object is known (see JP 2004-170165(A), JP H08-082671(A), and JP H04-054478(A)).
Because the fake image is unnecessary in the radar image, it is need to be removed. However, the conventional radar apparatus is not typically equipped with a function to appropriately identify such a fake image and reduce the fake image.